A tank of refrigerants getting refilled
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Breaking the ice on refrigerants

Understanding Refrigerants: Their Role and Evolution in Cooling Technology

Daren Wang
January 22, 2024

Throughout most of human history, generating warmth was a simple task. Early humans mastered the use of fire, requiring just a spark and some dry wood to produce heat. However, cooling things down was a different story, akin to the complexity of time travel.

It wasn't until the mid-1800s that the ability to create artificial ice became possible, followed by Willis Carrier's invention of air conditioning sixty years later. The principle behind air conditioners is straightforward: as gas expands, it loses heat. This principle is at the core of various cooling systems, including refrigerators, freezers, heat pumps, and air conditioners, which all operate by compressing and expanding gas to cool their surroundings.

The effectiveness of these systems hinges on special gases known as refrigerants. These substances have unique properties that allow them to transition from liquid to gas and back to liquid at relatively low temperatures.

All these devices follow a similar process: compressing a refrigerant gas to emit heat as it becomes liquid, then allowing it to expand back into a gas in a coil, thereby cooling its environment. This cycle is repeated to maintain cooling.

In air conditioners, fans push warm indoor air over coils filled with refrigerant. The refrigerant, undergoing a phase change from liquid to gas, absorbs heat and cools the air. To continue effective cooling, the air conditioner reconverts the gas back into a liquid. This involves a compressor applying high pressure to the gas, generating additional heat, which is expelled outdoors through condenser coils and a secondary fan. As the gas cools down, it returns to a liquid state, restarting the cycle.

The air conditioner manages two key processes: chilling indoor air using refrigerant and compressing and cooling the resultant gas for its reversion to liquid.

However, not all gases are suitable as refrigerants. The composition of refrigerants has evolved over recent decades, influenced by environmental concerns and international agreements like the Montreal Protocol. Older refrigerants containing chlorine, harmful to the ozone layer, have been progressively replaced with more environmentally friendly alternatives.

The evolution of refrigerants began with the advent of compression systems. Initially, large cooling applications primarily used ammonia and carbon dioxide. However, smaller devices like home refrigerators and air conditioners require more efficient refrigerants. As such, new substances like sulfur dioxide and methyl chloride emerged for smaller refrigeration applications.

With advancing technology, centrifugal compressors became common in refrigeration, making methylene chloride a practical choice. Methylene chloride and carbon dioxide eventually found widespread use in large air conditioning systems. Modern cooling systems now employ more sophisticated compounds for increased efficiency.

Halocarbons, derived from methane and ethane by substituting hydrogen atoms with halogens like chlorine, fluorine, or bromine, include chlorofluorocarbons (CFCs). Common CFCs are CCl3F (R-11), CCL2F2 (R-12), and ChClF2 (R-22).

"Freon," a trademarked name by DuPont for R-22 coolant, is often used generically to refer to refrigerants. Other variants like R-12 and R-410A are also colloquially called Freon.

While Freon is considered relatively safe in maintained systems, the Environmental Protection Agency (EPA) recognizes its chronic toxicity risks and identifies it as an ozone-depleting substance. The EPA began phasing out R-22 in 2010, prohibiting its use in new air conditioners from January 1, 2010. Newer models using R-410A are more energy-efficient and less harmful to the ozone layer.

Over time, the variety of refrigerants has expanded, accompanied by evolving environmental and health concerns. Environmental laws have subsequently restricted options for servicing equipment.

Key Laws Regarding Refrigerants:

  • R-12 refrigerant, once the most popular refrigerant on the market, was banned in the early 1990s for contributing to the greenhouse gas effect and all production ceased in 1994.
  • R-22 refrigerant is less harmful to the ozone and became available in the late 1990s. It’s no longer in production and it will be entirely illegal by 2030 to comply with the Clean Air Act of 2010.
  • Refrigerant leaks must be fixed within 30 days and refrigerant must be recaptured, recycled, and disposed of properly by a certified technician to avoid fines.
  • Refrigerators and air conditioners need to be disposed of properly according to EPA regulations.

Another challenge is the varying refrigerant requirements of different systems, making it difficult to find suitable refrigerants for older systems as the most harmful ones are phased out.

When you are dealing with maintenance around your HVAC, refrigerator, or heat pump, don’t be afraid to ask questions. If you are adding refrigerant to an older system, make sure the refrigerant is compatible with the system. And with the cost of materials getting higher every year, consider sunsetting your older HVAC for a new system that runs on a more environmentally friendly refrigerant. It will save you money in the long run while you do the right thing for the environment.

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